(a) Technical Field
The present invention relates to a shift fork with improved abrasion resistance achieved by forming metal coating on a pad of the shift fork, which is a control system component of a manual transmission which changes stages of the transmission based on manipulation of a gearshift lever, and more particularly to a shift fork having excellent abrasion resistance in which a molybdenum (Mo) sprayed coating layer having a high hardness and an excellent abrasion resistance and a copper (Cu) sprayed coating layer having excellent low frictional characteristics are formed to have a multilayered structure.
(b) Description of the Related Art
In general, a gearshift lever is manipulated to change a speed of a vehicle according to a driving condition of the vehicle such that a gear ratio of the transmission receiving a rotating force of an engine can be changed, and the gear ratio of the transmission is manipulated by the medium of a shift fork which engages the gears according to the state of the transmission through manipulation of the gearshift lever.
The shift fork has a substantially U shape to apply a force while surrounding a gear of the transmission, that is, a sleeve, and is manufactured generally through die casting by using an aluminum alloy.
The existing shift fork is generally manufactured through die casting by using a hypereutectic aluminum alloy (R14) containing silicon (Si) through a hypereutectic process, but it is sufficient to provide only the portion of the shift fork that contacts the sleeve with a strong abrasion resistance. However, if the entire shift fork is formed with the hypereutectic aluminum alloy (R14), then excess material is used and processing efficiency is low, and thus manufacturing costs are high.
The conventional art discloses a method of manufacturing a shift fork including a method of forming an aluminum/alumina thick film at a portion of a shift fork contacting a sleeve using a low temperature spraying coating method. The coating layer formed through the method uses a hypereutectic aluminum alloy (ADC12) which is inexpensive as the material of the shift fork securing an abrasion resistance of a coating layer corresponding to the abrasion resistance of an existing hypereutectic aluminum alloy material as well as guaranteeing a sufficient attaching force, so that waste of the material can be prevented and processing efficiency can be increased. In particular, manufacturing costs can be remarkably reduced.
However, even in this case, abrasion resistance is not sufficient, and a surface of a coating layer may be peeled off by friction.